WASHINGTON  Senators of both parties expressed frustration Wednesday at the findings of an independent panel that blamed systemic failures in the State Department leadership for “grossly inadequate” security at the U.S. diplomatic mission in Benghazi, Libya, where the ambassador and three other Americans were killed in a Sept. 11 attack.

Emerging from a closed, 75-minute briefing with leaders of the panel, lawmakers said the harshly critical report identified problems that the State Department was moving to address.

“My impression is the State Department clearly failed the Boy Scout motto of be prepared,” said Sen. John Barrasso, R-Wyo. “They failed to anticipate what was coming because of how bad the security risk already was there. ... They failed to connect the dots. They didn’t have adequate security leading up to the attack and once the attack occurred, the security was woefully inadequate.”

Democratic Sen. Dick Durbin of Illinois said the Accountability Review Board found no “willful misconduct,” which is the standard for judgment.

“But it is also clear that there was a failure when it came to the management of security in Benghazi,” Durbin said. “As a consequence some internal administrative action is being taken in the State Department.”

On Wednesday, an administration official said Eric Boswell, the assistant secretary of state for diplomatic security, and Charlene Lamb, the deputy assistant secretary responsible for embassy security, stepped down under pressure after the release of the report. A third official who worked for the Bureau of Near East Affairs and wasn’t immediately identified, also resigned, the official said, speaking on condition of anonymity because he wasn’t authorized to discuss personnel matters publicly.